Auckland transport planners are considering closing Quay St to traffic on match days if the waterfront stadium plan goes ahead.
They would also open a foot tunnel between the ferry terminal and Britomart station to cater for stadium crowds.
Scheduled bus services will probably need to be extensively re-jigged to make room for dozens of shuttle vehicles around the railway station, which an Australian transport consultant for the rival Eden Park proposal says would have to be upgraded to cope with the multitudes teeming from a waterfront stadium.
Although Auckland City officials will not comment on traffic management before reporting to councillors next week, they are understood to be working on turning Quay St into a tree-lined boulevard and making it a pedestrian mall during large events at a 60,000-seat Stadium NZ, which would sit over Marsden Wharf and straddle Captain Cook and Bledisloe wharves.
They are also considering building a pedestrian tunnel between the ferry terminal and Britomart, a feature of the original proposal for a multi-modal transport centre which was dropped for cost reasons in favour of the existing $211 million underground railway station.
But that would provide only a relatively circuitous route to a waterfront stadium for thousands of spectators arriving by train, and Eden Park transport consultant Graeme Steverson said yesterday that he believed the back entrance at the eastern end of Britomart would need to be improved to funnel the crowds to railway platforms after rugby finals.
Extra ferries may also be pressed into service, but he believed these were too slow to cater for big events.
Sydney-based Mr Steverson, who has spent nine months working on a traffic management plan to allow an enlarged Eden Park stadium to cater for the 2011 Rugby World Cup, said he had only an hour to consider the rival waterfront proposal championed by the Government.
It would therefore be unfair to make a detailed comparison.
Even so, he said his team had identified a number of challenges transport officials would have to get to grips with to make a waterfront stadium work.
A fundamental requirement would be closing Quay St for rugby cup games and other big events.
"That is essential because it is the only side of the compass you have got to get everybody out of the stadium, so you can't have a live road there."
The question of where Quay St's regular traffic would go was "a biggie".
Mr Steverson said that although the waterfront site was well located in regard to public transport links, these were for regular services needed to satisfy normal demands below the level of stadium events.
A big plus for Eden Park would be an underground bus drop-off area under a pedestrian concourse around an enlarged stadium, which a waterfront venue would be unable to accommodate unless pushed 30m to 40m back from Quay St towards the sea.
Such a feature would add about $9.75 million to the cost of a waterfront stadium. Nor had he seen plans identifying an event-specific transport plan for Stadium New Zealand.
But he said that in the absence of an on-site bus station, room would have to be made around the Britomart centre for shuttle vehicles, meaning the terminus for regular services in lower Queen St might have to be relocated.
Mr Steverson said the Eden Park plans included provision for about 25,000 people - or about 40 per cent of a capacity crowd of 60,000 - to travel to and from events by public transport.
That would include 15,000 by train, which was double the current capacity of Kingsland Station, and 10,000 by event-specific bus services or coaches.
An enlarged 1km exclusion zone, in which only residents or a limited number of their visitors would be allowed to park, would encourage greater public transport use in a way he doubted would be possible around a waterfront venue.
And although there were 10,000 public parking spaces around central Auckland, stadium crowds would have to compete for space with those attending other events such as at the Vector Arena and The Edge.
The rail target for Eden Park would be achieved with a $26 million station upgrade including a pedestrian concourse over the tracks from New North Rd and into Eden Park and a "lid" over Kingsland's two platforms.
On match nights, trains would head back to Britomart on both platforms.
Kingsland would cater for about 13,000 passengers, leaving an upgraded Morningside station to carry a further 2000 in a westerly direction.
The main pressure point for rail was not so much bringing passengers to games, as they could be staggered over two hours or longer, but getting them away afterwards.
That was because people became "too anxious" if it took longer than 75 minutes to get away.
Mr Steverson said that although Britomart would be able to disperse 13,000 passengers arriving from Kingsland in that time, it would be hard-pressed coping with such a number streaming on to platforms from a waterfront stadium.